<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>保留字 debugger</title>
    <script>
        function tessDebugger(){
            var  x = 15 * 5;
            debugger;
            document.getElementById('demo').innerHTML = x;
        }
    </script>
</head>
<body>
    <p id="demo"></p>
    <p>开启 debugger ，调试模式下代码会在 debugger 处停止执行。</p>
   <button onclick="tessDebugger()">测试一下debugger函数</button>
</body>
</html>